Huawei YU220, Service Manual

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YU220 service manualV1.0
2013-10-18
Huawei secrets, no dispersion without permission
Fault analysis process：
CTP failure is generally unresponsive touch, unresponsive, touch point bounce,
etc., please replace the new CTP, see if you can solve the problem, if it
still cannot be solved, according to the following steps：
1、Input power is normal, if the input voltage is abnormal, first determine
whether a short circuit, remove the capacitors on the line after the short circuit。
Measurement, there may be chips and connectors J902 U501 causing a short
circuit can be re-welded and then measuring
2 、 Reset signal is pulled up, if the working time is low, the CPU
exception, can be welded and then measuring.
3、Is there a control signal output, use the oscilloscope to measure whether
thereSDA0 and SCL0 signal output, if abnormal, U301 body bad.